Authors:

BARENSE, M.D., HENSON, R.N.A. & Graham, K.S.

Reference:

Year of publication:

2008

CBU number:

6769

Abstract:

Recent studies indicate that structures in the medial temporal lobe (MTL) support processes beyond long-term declarative memory, including perception. In addition, there appears to be an influence of stimulus meaningfulness on discrimination ability in patients with temporal lobe damage. For example, discrimination performance in patients with focal MTL lesions (e.g., from herpes viral encephalitis) was improved by the use of meaningful stimuli. By contrast, patients with semantic dementia, a neurodegenerative condition characterised by progressive deterioration of conceptual knowledge and atrophy to the anterolateral temporal lobes, showed no benefit from the use of meaningful stimuli. To further investigate these findings, healthy volunteers were scanned while they performed oddity discriminations involving familiar and unfamiliar objects and faces. Across the different conditions, different patterns of temporal lobe activation were observed. Discriminations involving familiar stimuli were associated with activity in the perirhinal cortex, anterior hippocampus, amygdala and temporal pole when compared to oddity judgements for unfamiliar stimuli. When compared to object discriminations, face oddity judgements were associated with activity in anterior temporal lobe structures, including the anterior hippocampus, perirhinal cortex, amygdala and temporal pole. These observations provide further evidence that the MTL is recruited during complex visual discriminations which place minimal demand on memory.